I have a set of about 20 embedded Unix clients who physically move from time to time. When they move into the range of a specific wireless AP, they will push a certain set of files to a Windows file server in the LAN. Every client will send a 250Mib file. There will never be any remote access to this LAN.
It basically looks like a train (embedded Raspbian clients) on a traintrack collecting passengers (the files) and then dropping them off at a specific point (The windows server).
I only want to push files to this Windows server and get an acknowledgement that it completed or not. I don't want or need anything else. I'm not going to share files between the clients or the server, files won't be modified or anything else than just a barebones bulk upload of files. The clients will never interact in any other way with the server or files other than uploading them. The server will process these files further.
I have read the following questions and answers: 1, 2, 3 but found that the use cases presented there did not match mine as these all request and consider features I don't need.
To summarize: Which protocol is most suitable for solely uploading files to a server?